A machine tool (EPA 0 180 146) which is a multi-stamp machine tool with at least three, often with five die holding fixtures disposed side by side in the upper die support, with upper dies, in particular stamping punches disposed therein, and a corresponding number of lower die holding fixtures with corresponding lower dies, in particular punch dies is known.
The upper dies can be changed particularly quickly, either individually or as a whole, because a locking cap, which secures all die holding fixtures on the upper die support at their front ends, is pivotably linked with the upper die support and can be locked with it. When the locking cap is opened, each individual upper die or all upper dies together can be simply pulled horizontally out of the die holding fixture which is horizontally opened on one side, or, correspondingly, other upper dies can be horizontally inserted.
The die holding fixtures at the lower die support are located in a matrix plate which, in turn, is inserted in the frame of a saddle plate. The matrix plate can always be placed into its desired position in a few steps by inserting the matrix plate into the frame of the saddle plate and locking it in this frame. The number of upper and lower dies which can be used simultaneously depends on the number and size of the upper and lower dies. Depending on the number and size of the lower dies, there are different exchangeable matrix plates available.
It is known per se, in connection with machine tools having an upper and a lower die, to combine the upper die and the lower die in a tool unit including a guide frame, in particular, in a cutting unit or coping unit (German Published, Examined Patent Application DE-AS 10 04 891). This known machine tool has a coping unit as a tool unit. The upper die is vertically guided in guide rails of a guide frame and has at its upper end hammerhead-shaped coupling means, into which corresponding coupling means on the upper die support, in this case, in the shape of a T-groove, can be inserted. The guide frame of the tool unit receiving the lower die has as coupling means at its lower end, a plate in the shape of an inverted T, into which coupling means in the shape of a T-groove on the lower die support can be inserted. Thus, in this known machine tool, the entire tool unit is engagingly inserted as a whole in the longitudinal direction of the machine frame from the open front end between the upper and lower die supports. This is particularly practicable because it permits a quick and rapid exchange of the work unit due to the self-guidance of the dies in the tool unit, and it is possible at the same time to compensate for or to absorb within the tool unit, lateral forces occurring during cutting or coping.
However, this known machine tool with a tool unit is not sufficiently flexible in that, for bevel cuts with different angles, it is necessary to exchange one tool unit between two cuts for another tool unit having the next required bevel angle.